Magnetic print rolls for magnetic attachment, support, and driving carriage of ferro-magnetic flexible printing plates, embossing dies, or sheet cutting dies commonly present radially outwardly extending register pins. Such pins conventionally serve a function of engaging pin receiving eyes or apertures positioned along and extending through a leading edge of a flexible ferro-magnetic plate to be attached to the roll. Upon engagement of such register pins with such eyes or apertures, a correct alignment of the plate's edge is desirably produced. Thereafter, the flexible ferro-magnetic plate may be wrapped about the magnetic roll to produce a secure and correctly aligned magnetic plate attachment from the leading edge of the plate to its trailing edge. In many circumstances, small deviations in plate position away from a properly aligned orientation may be corrected by manipulating the conventionally provided roll position adjustment mechanisms of a printing press in which the magnetic roll is installed.
Where a magnetic roll is used for magnetically attaching, supporting, and driving a matched pair of ferro-magnetic flexible printing plates (each extending semi-circumferentially about the roll), two pairs of such plate aligning register pins are conventionally provided, one pair of register pins being used to establish the alignment of each plate upon the roll. However, upon installing a pair of such plates, an operator often finds that the printing press's print roll alignment mechanisms are incapable of correctly aligning both plates among the pair. The operator may manipulate the press's roll position adjustment mechanism to achieve a correct position and alignment of a first plate among such pair without achieving a correct alignment of the second plate. Instead of achieving a correct alignment of the second plate, a printing press actuated correct alignment of the first plate may exacerbate any misalignment of the second plate.
The instant inventive magnetic roll solves or ameliorates the problems, defects, and deficiencies discussed above by specially adapting a magnetic roll for adjustment and movement of a pair of its register pins by incorporating within the roll a moveable plate mechanism, such mechanism being consonant with and avoiding any significant interruption of needed continuity of plate attaching magnetic field strength at the circumferential locus of such mechanism.